// © Broadcom. All Rights Reserved.
// The term "Broadcom" refers to Broadcom Inc. and/or its subsidiaries.
// SPDX-License-Identifier: Apache-2.0

package find

import (
	"context"
	"os"
	"path"
	"strings"

	"github.com/vmware/govmomi/list"
	"github.com/vmware/govmomi/object"
	"github.com/vmware/govmomi/property"
	"github.com/vmware/govmomi/vim25/mo"
)

// spec is used to specify per-search configuration, independent of the Finder instance.
type spec struct {
	// Relative returns the root object to resolve Relative paths (starts with ".")
	Relative func(ctx context.Context) (object.Reference, error)

	// ListMode can be used to optionally force "ls" behavior, rather than "find" behavior
	ListMode *bool

	// Contents configures the Recurser to list the Contents of traversable leaf nodes.
	// This is typically set to true when used from the ls command, where listing
	// a folder means listing its Contents. This is typically set to false for
	// commands that take managed entities that are not folders as input.
	Contents bool

	// Parents specifies the types which can contain the child types being searched for.
	// for example, when searching for a HostSystem, parent types can be
	// "ComputeResource" or "ClusterComputeResource".
	Parents []string

	// Include specifies which types to be included in the results, used only in "find" mode.
	Include []string

	// Nested should be set to types that can be Nested, used only in "find" mode.
	Nested []string

	// ChildType avoids traversing into folders that can't contain the Include types, used only in "find" mode.
	ChildType []string
}

func (s *spec) traversable(o mo.Reference) bool {
	ref := o.Reference()

	switch ref.Type {
	case "Datacenter":
		if len(s.Include) == 1 && s.Include[0] == "Datacenter" {
			// No point in traversing deeper as Datacenters cannot be nested
			return false
		}
		return true
	case "Folder":
		if f, ok := o.(mo.Folder); ok {
			// TODO: Not making use of this yet, but here we can optimize when searching the entire
			// inventory across Datacenters for specific types, for example: 'govc ls -t VirtualMachine /**'
			// should not traverse into a Datacenter's host, network or datatore folders.
			if !s.traversableChildType(f.ChildType) {
				return false
			}
		}

		return true
	}

	for _, kind := range s.Parents {
		if kind == ref.Type {
			return true
		}
	}

	return false
}

func (s *spec) traversableChildType(ctypes []string) bool {
	if len(s.ChildType) == 0 {
		return true
	}

	for _, t := range ctypes {
		for _, c := range s.ChildType {
			if t == c {
				return true
			}
		}
	}

	return false
}

func (s *spec) wanted(e list.Element) bool {
	if len(s.Include) == 0 {
		return true
	}

	w := e.Object.Reference().Type

	for _, kind := range s.Include {
		if w == kind {
			return true
		}
	}

	return false
}

// listMode is a global option to revert to the original Finder behavior,
// disabling the newer "find" mode.
var listMode = os.Getenv("GOVMOMI_FINDER_LIST_MODE") == "true"

func (s *spec) listMode(isPath bool) bool {
	if listMode {
		return true
	}

	if s.ListMode != nil {
		return *s.ListMode
	}

	return isPath
}

type recurser struct {
	Collector *property.Collector

	// All configures the recurses to fetch complete objects for leaf nodes.
	All bool
}

func (r recurser) List(ctx context.Context, s *spec, root list.Element, parts []string) ([]list.Element, error) {
	if len(parts) == 0 {
		// Include non-traversable leaf elements in result. For example, consider
		// the pattern "./vm/my-vm-*", where the pattern should match the VMs and
		// not try to traverse them.
		//
		// Include traversable leaf elements in result, if the contents
		// field is set to false.
		//
		if !s.Contents || !s.traversable(root.Object.Reference()) {
			return []list.Element{root}, nil
		}
	}

	k := list.Lister{
		Collector: r.Collector,
		Reference: root.Object.Reference(),
		Prefix:    root.Path,
	}

	if r.All && len(parts) < 2 {
		k.All = true
	}

	in, err := k.List(ctx)
	if err != nil {
		return nil, err
	}

	// This folder is a leaf as far as the glob goes.
	if len(parts) == 0 {
		return in, nil
	}

	all := parts
	pattern := parts[0]
	parts = parts[1:]

	var out []list.Element
	for _, e := range in {
		matched, err := path.Match(pattern, path.Base(e.Path))
		if err != nil {
			return nil, err
		}

		if !matched {
			matched = strings.HasSuffix(e.Path, "/"+path.Join(all...))
			if matched {
				// name contains a '/'
				out = append(out, e)
			}

			continue
		}

		nres, err := r.List(ctx, s, e, parts)
		if err != nil {
			return nil, err
		}

		out = append(out, nres...)
	}

	return out, nil
}

func (r recurser) Find(ctx context.Context, s *spec, root list.Element, parts []string) ([]list.Element, error) {
	var out []list.Element

	if len(parts) > 0 {
		pattern := parts[0]
		matched, err := path.Match(pattern, path.Base(root.Path))
		if err != nil {
			return nil, err
		}

		if matched && s.wanted(root) {
			out = append(out, root)
		}
	}

	if !s.traversable(root.Object) {
		return out, nil
	}

	k := list.Lister{
		Collector: r.Collector,
		Reference: root.Object.Reference(),
		Prefix:    root.Path,
	}

	in, err := k.List(ctx)
	if err != nil {
		return nil, err
	}

	for _, e := range in {
		nres, err := r.Find(ctx, s, e, parts)
		if err != nil {
			return nil, err
		}

		out = append(out, nres...)
	}

	return out, nil
}
